- Relative reactivity of hydroxyl groups in inositol derivatives: role of metal ion chelation
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O-Alkylation of myo-inositol derivatives containing more than one hydroxyl group via their alkali metal alkoxides (sodium or lithium) preferentially occurs at a hydroxyl group having a vicinal cis-oxygen atom. In general the observed selectivity is relatively higher for lithium alkoxides than for the corresponding sodium alkoxide. The observed regioselectivity is also dependent on other factors such as the solvent and reaction temperature. A perusal of the results presented in this article as well as those available in the literature suggests that chelation of metal ions by inositol derivatives plays a significant role in the observed regioselectivity. Steric factors associated with the axial or equatorial disposition of the reacting hydroxyl groups do not contribute much to the outcome of these O-alkylation reactions. These results could serve as guidelines in planning synthetic strategies involving other carbohydrates and their derivatives.
- Devaraj, Subramanian,Jagdhane, Rajendra C.,Shashidhar, Mysore S.
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experimental part
p. 1159 - 1166
(2009/10/04)
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- Achievement of ring inversion of myo-inositol derivatives due to silyloxy/silyloxy repulsion enhanced by the trans-substituents on both sides
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The introduction of quite bulky trialkyl or diarylalkylsilyl groups into vicinal trans-hydroxy groups induced a conformational flip of certain multifunctionalized cyclohexane rings from the usual chair form possessing more equatorial substituents (equatorial-rich chair form) into another chair-form that has more axial substituents (axial-rich chair form). This realization was experimentally revealed by the conformational study of the synthetic myo-inositol derivatives possessing two tert-butyldimethylsilyl (TBS), two triisopropylsilyl (TIPS), or two tert-butyldiphenylsilyl (TBDPS) groups on an adjacent trans-diol. Among them, the cyclohexane rings of the 4,5-bis-O-TIPS-myo-inositol, 4,5-bis-O-TBDPS-myo-inositol, and 1,2,3,6-tetra-O-benzyl-4,5-bis-O-TBDPS-myo-inositol were in the axial-rich chair form. Comparison of the ring conformations also revealed that the order of the repulsion was OTBDPS/OTBDPS>OTIPS/OTIPS>OTBS/OTBS, and the silyloxy/silyloxy repulsion was enhanced when the two silyloxy groups were placed in the center of the contiguous four equatorial substituents.
- Okajima, Kotaro,Mukae, Tatsuya,Imagawa, Hiroshi,Kawamura, Yoshiaki,Nishizawa, Mugio,Yamada, Hidetoshi
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p. 3497 - 3506
(2007/10/03)
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- Stable axial-rich chair conformer of myo-inositol derivatives due to introduction of two adjacent bulky silyl protections
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The ring-conformational change of myo-inositol derivatives by introducing two tert-butyldimethylsilyl, triisopropylsilyl, or tert-butyldiphenylsilyl groups into the 1,2-trans hydroxy groups - 3,4- and 4,5-positions - were investigated. The cyclohexane cores of the 4,5-bis-O-silylated derivatives with tert-butyldiphenylsilyl or triisopropylsilyl groups were present in the axial-rich chair form.
- Yamada, Hidetoshi,Okajima, Kotaro,Imagawa, Hiroshi,Mukae, Tatsuya,Kawamura, Yoshiaki,Nishizawa, Mugio
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p. 3157 - 3160
(2007/10/03)
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- Practical synthesis of all inositol stereoisomers from myo-inositol
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Synthesis of six inositol stereoisomers was successfully carried out via conduritol intermediates prepared from myo-inositol. Dihydroxylation and epoxidation followed by ring opening of the conduritol B, C and F derivatives gave epi-, allo-, muco-, neo-, DL-chiro- and scyllo-inositol. The cis- inositol derivative, which may not be prepared by this approach, was synthesized in 5 steps via 2-O-benzoyl-myo-inositol orthoformate as the key intermediate.
- Chung, Sung-Kee,Kwon, Yong-Uk
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p. 2135 - 2140
(2007/10/03)
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- The synthesis and resolution of (+/-)-1,5,6-tri-O-benzyl-myo-inositol
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Racemic 1,5,6-O-benzyl-myo-inositol was prepared by five routes and converted into 1,5,6-tri-O-benzyl-2,3-O-isopropylidene-myo-inositol, the camphanates of which were readily separated by chromatography.The absolute configurations of the chiral derivative
- Desai, Trupti,Fernandez-Mayoralas, Alfonso,Gigg, Jill,Gigg, Roy,Payne, Sheila
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p. 105 - 123
(2007/10/02)
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- Total synthesis of myo-inositol polyphosphates from benzene via conduritol B derivatives
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The four (±)-myo-inositol phosphates 1,4,5-IP3 (1), 2,4,5-IP3 (15), 1,2,4,5-IP4 (17) and 4,5-IP2 (19) have been synthesised from benzene, using the protected conduritol B (10) as the key intermediate.
- Carless, Howard A. J.,Busia, Kofi
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p. 3449 - 3452
(2007/10/02)
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- The Allyl Group for Protection in Carbohydrate Chemistry. Part 18. Allyl and Benzyl Ethers of myo-Inositol. Intermediates for the Synthesis of myo-Inositol Triphosphates
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Racemic 1,2:4,5-di-O-isopropylidene-myo-inositol was converted into racemic 1,2,4-tri-O-benzyl-myo-inositol, 1,2,4-tri-O-p-methoxybenzyl-myo-inositol and 2,4,5-tri-O-benzyl-myo-inositol using allyl groups for 'temporary' protection.The benzyl ethers are required as intermediates for the synthesis of the 'second messenger', inositol 1,4,5-triphosphate and its metabolite, inositol 1,3,4-triphosphate. 1,2,3,4-Tetra-O-benzyl-myo-inositol, and its two monoallyl and monoprop-1-enyl ethers, were also prepared as model compounds for phosphorylation studies of the vicinal 5,6-diol system which occurs in 1,2,4-tri-O-benzyl-myo-inositol.
- Gigg, Jill,Gigg, Roy,Payne, Sheila,Conant, Robert
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p. 423 - 430
(2007/10/02)
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- THE ALLYL GROUP FOR PROTECTION IN CARBOHYDRATE CHEMISTRY. PART 21. (+/-)-1,2:5,6- AND (+/-)-1,2:3,4-DI-O-ISOPROPYLIDENE-MYO-INOSITOL. THE UNUSUAL BEHAVIOUR OF CRYSTALS OF (+/-)-3,4-DI-O-ACETYL-1,2,5,6-TETRA-O-BENZYL-MYO-INOSITO ON HEATING AND COOLING: A '
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Racemic 1,2-O-isopropylidene-myo-inositol was converted into a mixture of 1,2:5,6-, 1,2:3,4-, and 1,2:4,5-di-O-isopropylidene-myo-inositols which were resolved by g.l.c.The 1,2:4,5 and 1,2:5,6- isomers were isolated from the mixture as benzoate derivative
- Gigg, Jill,Gigg, Roy,Payne, Sheila,Conant, Robert
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p. 2411 - 2414
(2007/10/02)
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